Brake for railroad switch machines



Sept. 22, 1931. w. K. HOWE BRAKE FOR RAILROAD SWITCH MACHINES Filed Oct.14, 1929 2 Sheets-Sheet 1 INVENTOR 1 Y 1a 7b? W. K. HOWE Sept. 22, 1931.

Filed Oct. 14, 1929 2 Sheets-Sheet 2 Y E N m T T A Patented Sept. 22,1931 UNITED" STATES- PATENT OFFICE;

WIN'IHROP K. HOWE, 01E ROCHESTER; NEW YORK; ASSIGNOR T GENERAL RAILWAYSIGNAL'GOMPANY, 0F ROCHES'IER, ZN'EW' YORK BRAKE FOR RAILROAD .SW'ITGH.MACHINES Application filed October 14, 1929. Serial No. 399,549.

This-invention relates to devices used for the control of railroadtrack'switches, and more particularly pertains to a mechanical brake tobe used with switch machines oper- 6 ating such switches.

'It is found in practice to be an essential factor of safety, that nomovement of a track switch should be allowed except under authorizedcontrol. In some cases however, the 10 switch points are operated to thedesired extreme position with the switch machine failing to lock thetrack switch, due to the opening of an over-load device. the failure ofparts, or the like, which condition results 16 in the display of a stopindication by the governing signal. But the tower operator, or otherofficial, desiring to facilitate the movement of traffic, orders thetrain to proceed'under flag, that is, send a flagman ahead 20 of thetrain which then proceeds over the apparently locked switch points.

Such a caseas pointed out above, is not so dangerous with the so calledtrailing point moves of trains, while the facing point moves produce avery undesirable hazard, in that the passage of the train produces avibration and weaving of the track-rails which may open the switchpoints enough to engage a thin car wheel flangecausing a split train;

One object of the present invention is to provide means whereby such acontingency,

as pointed out above, shall be provided for by the use of a mechanicalbrake, which brake is eifective to prevent movement of the switch pointsat all times when the track switch is unlocked and its controllingswitch machine motor is not supplied with authorized control power.

Other objects, purposes and characteristic 10 features will be in partobvious from the ac companying drawings and in part pointed out-as thedescription of the invention progresses. g g

In describing the invention in detail, ref- 4 erence will be made to theaccompanying drawings, in which like reference characters indicatecorresponding parts in the several views, and in which:

- Fig. 1 is a diagrammatic representation of 5 a motor of a switchmachine and the switch machine controlling mechanisms for a track switchwith the brake of the present invention shown interposed betweenthe'switch machine motor and the mechanisms which are controlledthereby;

Fig. 2 is an end view of a mechanical brake shown as one specificembodiment of the present invention with parts shown in section astakenon the line 22 of Fig. 3

' Fig! 8 is a cross section of the mechanical brake of the'presentinvention taken on the line 3 -3 of Fig. 2.

WVit'h reference to Fig. l of the drawings, there is shown in adiagrammatic manner a track switch TS controlled by any suitableSWltCl11X1LCl1lI1,-SI10l1 as set-forth in my Paten-t 'No.- 1,466,903,dated September, 1923, with the brake B, as'the specific embodiment ofthepresent inventiom'interposed between the motor 'M and the variousmechanisms of the switch-machine. As the operation and construction ofsuch a switch machine is completely disclosed in my above referred topatent, it is deemedunnecessary to describe the operationandconstruction of the switch machine, otherthan is necessary to explainthe operation of the present invention.

The motor Mmay be controlled in any well knownmanner, for example, .asset forth in my Patent No.- l,550,611,: dated August 18, 1925, and isshown as controlled-over the normal and reverse control wires N and'R-inconjunction -with.a common wire 0 (see Fig. 1). The torque produced bythe motor M during operation, is transmitted through the brake i B tothe pinion 1 which meshes with a bevel gear 2. This bevel gear 2 isconnected with a friction clutch. K, which in turn 'is con nected to thepinion 3, which pinion meshes with a gear 4. The gear 4 drives a pinion5, whichin turn operates the main drive gear 6 'of the switchmachine. ia The initial movement of the main drive gear 6 in either a reverseor anormal direction, that is,:in a direction to control the track switch TSto a normal or to a reverse position respectively, controls the lockplunger LP through a considerable distance before a lock dog LD"disengages a throw-bar TB and before theilockvdog LD disengages the lockrods LE and LR, at which time the main drive gear 6 operates thethrow-bar TB to an opposite extreme position. The movement of thethrow-bar TB operates the track switch TS from an extreme normalposition to an extreme reverse position, which movement also operatesthe lock rods LE and LE to reverse positions. With the throw bar TB andthe lock rods LE and LE in reverse positions, the main drive gear 6continues rotation, which moves the lock plunger LP to such a positionthat the lock dog Ll) again engages the throw bar TB and the lock dog LDagain engages the lock rods LE and LE From the above description, it isobvious that the motor M can only operate the track switch TS at suchtimes that the track switch is unlocked, and conversely, any forceapplied to the track switch can only tend to operate the switch machinemechanism at such times that the track switch is unlocked. Thus, theprovision of the brake B which permits the motor M to operate the trackswitch TS and which prevents the track switch from operating the motor.accomplishes the desired result in that the track switch is preventedfrom movement at all times during which power is not ap lied to theswitch machine motor.

With reference to Fig. 3. a rake drum ED is provided as integral withthe motor frame 7. and is also suitabl ioined with a portion ot theswitch machine frame 8. A motor shaft passes through. and is iournalledin the motor frame 7. This motor shaft 9 furnishes a bearing for the p non 1 which meshes with the gear Two brake shoes 10 and 11 are secured tothepinion l b the pins 12 in such a m nner-tha two sp ings 13 and 1evpapd he liralr hoe 10 and 11 until br ke l n n s 15 and 16 come intocontact ith he lralrinq surface oi he h alze drum B11 The piv t o ntsfurn sh d h the ins ar in su h posi on that the .s-nrino' 13 tends t h sor for he brake shoe 11 a ainst the b ake drum BI). While th shrine- 14tend to bias o for e hra e sho l0 a' ain t t e brake drum B ee Fin, ll.with su h an arrangement. toroue is applied o the in on 1.it cannotrotate due o the braking effect of th brake shoes 0 and 11. 7

To' accompl sh the compression of the springs 13 and Hand to allow thetoroue applied to the shaft 9 tohetransmitted to the pinion 1, a drivemember 17 is keyed to the shaft 9 by akev member 24 and is furthersecured by a pin 25 (see Fig. 3) .i This drive member 17 has'arms 17 and17 which serve as'pivot points for links 18 and 19, attached to theirrespective arm supports by means of pins 20 and These links 18 and 19are pivotally attached to the brake shoes 10 and 11 respectively atintermediate points between t-he pivot points 12 and the points at whichthe springs 13 and 14 apply expanding pressure to their respective brakeshoes (see Fig. 2

When torque is applied to the shaft 9 by the motor M in eitherdirection, forces are transmitted through the links 18 and 19 which aredivided into component forces, so that certain compressing componentstend to compress the springs 13 and 14:, and certain other rotationalcomponents tend to rotate the brake shoes 10 and 11 in a directiondepending upon the direction of the torque provided by the motor M. Itis further seen. when the compressing component forces are of sufiicientvalue to compress the springs 13 and 14, that the braking efi'ect iseliminated and the pinion 1 is caused to rotate with the brake shoes 10and 11 in a direction in accordance therewith, thus controlling thetrack switch TS to a corresponding position.

The component forces causing the compression of the brake shoes 10 and11 against the bias of the springs 13 and 14. continues to compressthese brake shoes so that they come into contact with the arms 17 and 17of the drive member 17. Such a position is maintained by the brake shoes10 and 11 during the operation of the motor M, with the brake shoesexpanding and assuming a braking position against the brake drum BD assoon as the motor ceases to receive power to drive the load.

Thus, when the track switch TS is unlocked, it is prevented frommovement if the governing motor is not supplied with power, due to thebrake of the present invention which is normally biased to a brakingcondition. However. it the governing motor is energized suiiicient tonormally operate theswitch machine. the brake is first released and thencontinuously held in a released condition as long as an active drivingtorque is supplied to the switch machine. v

It is obvious that the mechanical brake of the present invention may beused with other types of switch machines than the specific type shown.Also, other applications of such a brake could be made, such as use witha car retarder mechanism or the like, or in other such cases where thereis a driven element and a driving element.

Having described one specific embodiment of a mechanical brakeconstructed according to the present invention. it is to be understoodthat many alterations, modifications andv adaptations may be applied tothe present invention to meet the requirements of practice withoutdeparting from the spirit or scope of the invention as set forth in theappended claims.

Having described my invention, I now claim 1. For use with a railroadtrack switch and a power driven switch machine, a mechanical brakeincluding, a fixed brake drum, two brake shoes Within said fixed brakedrum biased to engage said brake drum, means disengaging said brakeshoes from said brake drum upon application of power to said switchmachine including, a power driven shaft of said switch machine, aplurality of arms upon said power driven shaft, and means movablyconnecting said arms to said brake shoes, whereby rotation of said shaftin either direction in respect to said brake shoes disengages said brakeshoes from said brake drum, and means operably causing said brake shoesto rotate with said shaft after said braking effect has been eliminated,including stops provided by said brake shoes and engaging said arms onsaid power driven shaft.

2. For use with a track switch for railroads and a power driven switchmachine, a

mechanical brake including, a fixed brake drum, a pinion drive member,two brake shoes pivotally attached to said pinion drive member, two coilsprings biasing said brake shoes to engage said fixed brake drum, apower driven. shaft, two drive arms on said power driven shaft, twolinks with each of said links pivotally attached respectively to one ofsaid drive arms and pivotally attached to one of said brake shoesrespectively, whereby said power driven shaft can operate said piniondrive member, and Whereby said pinion drive member cannot operate saidpower driven shaft.

3. For use with a track switch for railroads and a power driven switchmachine, a mechanical brake including, a fixed brake drum, a piniondrive member, two brake shoes within said fixed brake drum havingopposite extreme ends pivotally attached to said pinion drive member,two coil springs each of which bias one of said brake shoes to engagesaid brake drum, a power driven shaft, two drive arms extending for aprede tel-mined distance toward said brake shoes from said power drivenshaft, two links each of which is pivotally attached to the one of saidbrake shoes opposite said drive arm, whereby said power driven shaft cancompress said springs until said brake shoes come into contact with saiddrive arms, and whereby torque on said power driven shaft will operatesaid pinion drive member with a certain minimum value of load reactionpresent upon said pinion drive member, and whereby said pinion drivemember cannot operate said power driven shaft.

In testimony whereof I affix my signature.

WINTHROP K. HOWE.

